Trippleton Lane

Exposed Units: Elton Formation (Lower Ludlow Shales), Upper Ludlow Shales

Conservation Status: Local Geological Site

A notable feature of this quarry is the absence of the Bringewood Formation and Aymestry Limestone that would normally lie in between the Lower and Upper Ludlow Shales. Instead, the Lower Leintwardine Formation of the Upper Ludlow Shales rests directly against the Elton Formation of the Lower Ludlow Shales. The contact between the two units is unfaulted and so represents an unconformity, or a time gap in the geological record.

All units here are dominated by grey or olive siltstone that is thinly bedded and often laminated. Thicker beds, up to 10cm, are in evidence and there are numerous examples of low angle current bedding. Harder grey nodules occur in places and there is one occurrence of a boulder with a siltstone drape. Some bedding planes contain abundant fauna, mainly small brachiopods and sparse graptolites, which correspond to the Lower Leintwardine Formation. This fossil assemblage continues along the outcrop for ~60 m where, on the right hand side, there is an abrupt lateral change to a soft khaki blocky mudstone with a prolific graptolite fauna. This lithology corresponds to the older Elton Formation. The sudden lateral change in lithology has been interpreted as a submarine channel, which was carved into the Elton Formation. This channel was then subsequently infilled by material from the younger Upper Ludlow Shales Group.

Photos

View along the land towards the quarry on Trippleton Lane.

A boulder lying in the bottom of the submarine channel, that has been buried by the Upper Ludlow Shales.

Well-defined bedding in the Elton Formation.

Current bedding in the Upper Ludlow Shales (in the thick bed to the right of the hammer shaft)

References

Allender, R., Holland, C.H., Lawson, J.D., Walmsley, V.G. & Whitaker, J.H.McD, 1960, ‘Summer Field Meeting at Ludlow’, Proceedings of the Geologists’ Association, vol.71, 2, pp.209-232.

Whitaker, J.H.McD., 1962, ‘The geology of the area around Leintwardine, Hertfordshire’, Journal of the Geological Society, vol. 118, 3, pp.319-351.

March 2011